By Robert Knight, PhD Published in Underwater Speleology, Vol 51 No3 Autumn 2024.
Clear, pure groundwater is the basis for life in Florida’s artesian springs. Remove flowing water and a spring is a sinkhole, a stagnant window into the dark limestone underworld. A spring’s functionality or “life” declines when its flow decreases, and it increases in proportion to flow. The living assemblage of plants and animals characteristic of a Florida spring is directly dependent upon the quantity of groundwater that “springs” forth from its limestone vent.
Healthy springs are alive. They efficiently capture and convert Florida’s abundant sunlight into plant and animal life. The waving eelgrass, sunfish, bass, turtles, alligators, manatees, otters, and birds that live in and around springs are the visible living parts of their watery environment.
And just like all other living things, when springs are deprived of water, they become unhealthy and eventually die.
Before 1900, when Florida’s human population was less than one million people, there were no electric-powered well pumps. Human groundwater consumption was negligible compared to the natural recharge of rainfall to the aquifer. Also before 1900, Florida’s springs had thousands of years of uninterrupted flow to nourish their complex and vast ecologies. The first Europeans who wrote about Florida’s springs were astounded by these natural aquaria that were home to countless fish and wildlife.
Healthy springs attracted the human imagination and became Florida’s first and most famous tourist attractions.
All life is dependent upon water, including human life. It takes from one to three days for an adult human to die from dehydration. Symptoms of dehydration are extremely painful. An adult human needs to ingest about one gallon of freshwater per day to thrive. Groundwater, the lifeblood of springs that once seemed endless, is finite. When humans consume groundwater there is less flow at our springs. Whether it’s a gallon or a million gallons, human use translates into correspondingly fewer gallons to support our springs and their dependent flora and fauna.
The question for those of us who wish to protect springs is: how much is too much? How much flow can a spring lose and still be healthy?
Marion County’s Silver Springs showed no apparent declining flows until the 1980s. Arguably once Florida’s best-known tourist attraction and the United States’s largest clear-water spring, Silver Springs received a failing grade for flow (an F based on an average 32 percent flow reduction) on its Springs
Health Report Card, published by the Florida Springs Institute. The 32 percent average flow reduction in the country’s largest spring is equal to 170 million gallons per day.
During the same monitoring period, Silver Glen, a spring that is relatively immune to human groundwater consumption due to its protected springshed located in the Ocala National Forest, had no apparent change in average flow.
As a first approximation, it is safe to say that Silver Springs has one- third less capacity to support aquatic life than it did forty or more years ago. As Silver Springs loses its groundwater inflow, it is literally dying a slow death.
State water managers have concluded that “Marion County should experience no water-supply issues for the next two decades.” This is a surprising conclusion considering that flows at Silver Springs have been declining dramatically for nearly 30 years. It was the water management district’s responsibility to establish a minimum flow for Silver Springs that would protect it from “significant harm.” In fact, their formal minimum flow determination facilitated the continuing loss of Silver Springs’s flows and has resulted in the declining health of the springs’ ecology.
Concerned parents view a failing grade on their child’s report card as a wake-up call to take strong action. As stewards of the health of our economic and natural resources, public officials should not ignore this failing grade or the plight of Silver Springs.
https://nsscds.org/wp-content/uploads/2024/10/UWS-Vol-51-No-3-2024-rev-single-pages.pdf
